Pipe marking


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Three ASME A13.1 pipe markers.

Pipe marking is the usage of labels, typically color coded, to identify the use, contents and flow direction of pipes inside of industrial and commercial buildings. This information assists personnel when carrying out maintenance and emergency personnel when responding to emergencies.

ANSI/ASME Standards

In the United States, Occupational Safety and Health Administration regulations recommend following American Society of Mechanical Engineers Standard A13.1-2015 - Scheme for the Identification of Piping Systems.[1]

The standard states that labels should be placed where easily viewed by a person standing near the pipe at any of the following points:[2]

  • Valves and flanges.
  • Approximately every 25 feet (7.6 m) to 50 feet (15 m) on straight sections.
  • A pipe passes through a wall or floor.
  • Any pipe direction changes, such bends or junctions.
A13.1-1996 [2]
Meaning Background Color Text Color Example
Hazardous materials[a] Safety Yellow Black
Non-hazardous liquids Safety Green White
Non-hazardous gases Safety Blue White
Firefighting materials Safety Red White
Sprinkler Water
Meaning Background Color Text Color Example
Flammables[b] & Oxidizers[c] Safety Yellow Black
Combustible Fluids[d] Safety Brown White
Lubricating Oil
Toxic and Corrosives Safety Orange White
Water Safety Green White
Compressed air/Non-hazardous gases Safety Blue White
Compressed Air
Firefighting materials Safety Red White
Sprinkler Water
Custom - Defined by user Safety Purple White
Fluid Name
Custom - Defined by user Safety Grey White
Fluid Name
Custom - Defined by user White Black
Fluid Name
Custom - Defined by user Black White
Fluid Name

2015 revisions

A 2015 style pipe marker with GHS signal word and symbols.

2015 revisions added oxidizing materials to the existing 'Flammables' classification. The other major change allowed and encouraged labels to incorporate the GHS signal word, hazard pictograms, and hazard statements. This addition helped identify additional dangers when dealing with materials that fit into multiple categories, like Hydrogen sulfide, which is both flammable and toxic.[2]


An IIAR Bulletin 114 pipe marker.

In 2014, the International Institute of Ammonia Refrigeration introduced a specialized label design for use when marking pipes associated with refrigeration systems using ammonia, including information such as the physical state, pressure and purpose in the system.[4]

NFPA 99C 2002

The National Fire Protection Association have a special labeling system in the standard for Health Care Facilities, such as hospitals and dentistry offices. This standard puts more emphasis on gases found in Medical gas supply systems, which consist of both oxidizing gases and gases that displace oxygen.[5]

Gas Background Color Text Color
Carbon Dioxide Gray Black or White
Helium Brown White
Medical Air Yellow Black
Oxygen Green White[e]
Oxygen/Carbon Mixtures Green White
Nitrogen Black White
Nitrous Oxide Blue White
Waste Anesthetic Gas Disposal Purple White
Medical Surgical Vacuum White Black
Non-Medical Air Yellow/White Diagonal Striped Black
Non-medical and Level 3 Vacuum Black/White Diagonal Striped Black (In box)
Laboratory Air Yellow/White Checkerboard Black
Laboratory Vacuum Black/White Checkerboard Black (In box)
Instrument Air Red White

See also


  1. ^ Explosives, flammables, corrosives, toxic, radioactive, extreme pressures/temperatures.
  2. ^ Flash point below 100 °F (38 °C; 311 K).[3]
  3. ^ Oxidizers were added in 2015 update.[3]
  4. ^ Fluids that can burn, but are not considered 'flammable', flash point at or above 100 °F (38 °C; 311 K).[3]
  5. ^ Background & Text color can be reversed.


  1. ^ Occupational Safety & Health Administration (November 2016). "1910.261 - Pulp, paper, and paperboard mills". osha.gov. Retrieved 21 March 2019. 1910.261(a)(3)(ii) Scheme for the Identification of Piping Systems, A13.1—1956.
  2. ^ a b c d Brimar Industries. "ANSI/ASME A13.1 2015" (PDF). Pipemarker.com. Archived from the original (PDF) on 21 March 2019. Retrieved 21 March 2019.
  3. ^ a b c NASA (17 November 2017). "GSFC-STD-8006 - Safety Standard for Ground piping Systems Color Coding and Identification". standards.nasa.gov/. Retrieved 21 March 2019.
  4. ^ International Institute of Ammonia Refrigeration. "Guidelines for: Identification of Ammonia Refrigeration Piping and System Components" (PDF). Archived from the original (PDF) on 21 March 2019. Retrieved 21 March 2019.
  5. ^ Craftmark Pipe Markers. "NFPA 99C 2002" (PDF). craftmarkid.com. Archived from the original (PDF) on 21 March 2019. Retrieved 21 March 2019.